RS-61443 (Mycophenolate mofetil), the morpholino-ethyl ester of mycophenolic acid (MPA), is being evaluated as an immunosuppressant agent for use following solid organ transplantation. MPA is a potent and specific inhibitor of de novo purine synthesis and blocks the proliferation of both T and B lymphocytes. This will be the first multi-center-controlled study evaluating the safety and pharmacokinetics of intravenous mycophenolate mofetil.